Light-emitting diodes or LEDs have been used for a few years to provide light for signaling devices (traffic lights, etc.) and indicators or sidelights of automotive vehicles. The advantage of diodes is their long lifetime, their luminous efficacy, their robustness, their low power consumption and their compactness, making devices employing them more durable, and meaning they require less maintenance.
More recently, light-emitting diodes have been used for automobile roofs, in particular panoramic laminated roofs with illumination by light-emitting diodes as described in document WO2010049638. The light emitted by the diodes is introduced via an edge face into the interior glazing pane, which forms a guide, the light being extracted from the glazing pane by a scattering layer (a layer such as an enamel layer containing dielectric scattering particles) on the glazing pane, the area of which defines the luminous pattern. The scattering layer is too visible to the user in the off state (turned off). The luminous glazing unit then has a very cloudy and even most often opaque appearance in the zone of the scattering layer.